Precipitation hardening

Conference · · TMS (The Metallurgical Society) Paper Selection; (USA)

OSTI ID:5442360

Ardell, A J ^[1]

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1. Univ. of California, Los Angeles (USA)

Precipitation hardening generally refers to the strengthening produced by precipitate particles that are sheared by dislocations moving under the influence of an applied stress. To understand it quantitatively it is essential to describe the statistics of dislocation-precipitate encounters, and the mechanisms of dislocation-precipitate interaction. These can be categorized, roughly, as either of short range or long range. Short range interactions are those in which a dislocation can interact only with particles that intersect its glide plane geometrically; order strengthening and stacking-fault strengthening are recognized examples. Long range interaction mechanisms involve interactions between dislocations and precipitates that do not geometrically intersect the glide plane; an example of strengthening by this mechanism is coherency strengthening. Hardening due to a modulus mismatch between precipitate and matrix is a hybrid process. Examples of the successes and failures of all of the current precipitation hardening theories are presented and discussed. It is demonstrated that theories involving short range interactions are quite successful quantitatively because the encounter statistics and interactions are understood, while the opposite is true for theories involving long range interactions. Two other important problems in precipitation hardening are considered: (1) Strengthening of alloys containing unusual size distributions of the same precipitate phase; (2) Superposition of strengthening mechanisms associated with a given precipitate. The scant literature on these topics is reviewed.

• OSTI ID: 5442360
• Report Number(s): CONF-840909--
• Conference Information: Journal Name: TMS (The Metallurgical Society) Paper Selection; (USA) Journal Volume: 56
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
DISTRIBUTION
GEOMETRY
HARDENING
LINE DEFECTS
MATHEMATICAL MODELS
MATHEMATICS
MECHANICS
PARTICLE SIZE
PARTICLES
PRECIPITATION
PRECIPITATION HARDENING
SEPARATION PROCESSES
SIZE
STATISTICS